Electric water heater



y 1956 J. F. ROWL EY 2,744,184

ELECTRIC WATER HEATER Filed Nov. 4, 1953 ATTORNEYS ELECTRIC WATER HEATER Joseph F. Rowley, Buffalo, N. 2.

Application November 4, 1953, Serial No. 390,158

4 Claims. (Cl. 219-38) This invention relates to water heating apparatus and is particularly concerned with electric water heaters in which no modification or cutting of the hot water storage tank is required.

It is an object of the invention to provide an electric water heater of the side-arm type in which a plurality of electrical heating elements may be employed.

Another object of the invention is to provide an electric water heater of the type described in which heat may be supplied to the water at two different points.

A further object of the invention is to provide an electric water heater of the type described in which the flow of water is facilitated.

Another object of the invention is to provide an electric water heater of the type described in which the water temperature may be quickly and efiiciently raised.

Still another object of the invention is to provide an electric water heater of the type described which is simple and durable while so constructed as to make repair or replacement of parts easy and inexpensive.

Other objects and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings in which:

Figure 1 is a vertical sectional view showing a hot water storage tank having associated therewith an electric water heater embodying the invention of the present application;

Figure 2 is a transverse sectional view taken on the line 2--2 of Figure 1;

Figure 3 is a transverse sectional view taken on the line 33 of Figure 1; and

Figure 4 is a transverse sectional view taken on the line 44 of Figure 1.

In the embodiment of the invention illustrated, the novel side arm electric water heater of the present invention is shown associated with a vertical hot water storage tank 11. The latter is provided with an inlet pipe 12 which extends to a point within the tank adjacent the bottom thereof and which is supplied with cold water through a service line 13. An outlet pipe 16 is threadedly mounted in an opening at the upper end of the tank 11 and is connected to a hot watersupply line 17. The tank ill is also provided at its bottom with a drain line 18 which may be furnished with a shut off valve or plug (not shown). The tank may be supported vertically in any desired manner such as by the stand 19.

The water heater which is generally designated by the reference character 22 is, as shown, located exteriorly of the tank ill and is supplied with water from the tank through a nipple 23, that communicates with the interior of the tank adjacent the bottom thereof, and a supply pipe 24 connected thereto. Hot water from the heater 22 is led back into the tank 11 adjacent the top thereof through a pipe connection 26.

The heater 22 comprises a casing 29 which is preferably cylindrical in cross section and has removable bottom and top portions 31 and 32, respectively. Within the casing 29 there is provided a pair of vertically spaced water-tube coils 34 and 35. These coils are preferably United States Patent 2,744,184 Patented May 1, 1956 formed of a metal having high heat conductivity, such as copper, and are constructed as flat spirals. As best shown in Figure 3, the lower coil 34 is preferably a spiral that progresses from its outside to its center in a clockwise direction when viewed from above, the inlet for water being provided in the end 37 which is connected to the supply pipe 24 by the elbow 38. The upper coil 35 is preferably also in the form of a spiral that, as viewed from above, is wound counter-clockwise from its inlet end to its center from which an axially extending outlet 39 projects outwardly through the top 32 of the casing 29 and is joined to the line 26 by the union 41. The outlet from the lower spiral coil 34 is joined, preferably permanently as by welding or brazing, to a tube 42 by which it is connected to the peripheral inlet of the upper spiral coil 35. To facilitate the flow of water through the heater the interior diameter of the tubing forming coil 35 is preferably substantially greater than that of the tubing in the lower coil 34. Thus, as the water expands during heating back presure is minimized and the rate of flow through the upper water-tube coil is not so great as to prevent proper heating therein.

An electrical heating element 44 is provided for each of the water-tube coils 34 and 35. The elements 44 are preferably metal-sheathed, tubular, resistance heaters and each is arranged, as best shown in Figure 4, as a plurality of convolutions held in a plane by a spider 46. One of the heating elements is removably supported by any convenient means within the casing 29 in contact with the fiat face of each of the spiral coils 34 and 35. Electrical connections 47 are attached to each heating element and extend to a control box 48 mounted in the side wall of the casing 29 and accessible from the outside of the casing.

To those skilled in the art the manner of operation of the novel water heater of the present invention will be easily understood from the following brief description. The storage tank 11 is filled with cold water through the line 13 and pipe 12, the supply pipe 24, the heater 22., and the pipe 26 being filled at the same time. When electrical energy is supplied to either or both of the heating elements 33 the heat generated is transferred to the water-tube coil or coils 34, 35 in contact therewith and the water in the coil or coils is heated and expands thus reducing its specific gravity and inducing upward flow and circulation of Water through the heater 22 from the bottom of the tank 11 to the upper end thereof according to the well-known thermo-syphon principle. Such circulation by connection will continue as long as the tank-heater system is full of water and heat is supplied to the water.

The provision of a plurality of heating elements permits a very advantageous flexibility in the operation of the water heater of the present invention as well as a notable economy in operation. Suitable thermostatic controls (not shown) may be installed in connection with the heater and connected to the control box 48 to regulate the supply of electric current to the heating elements 44 in such manner as to maintain the temperature of the hot water supply in the tank 11 substantially constant at a predetermined point. During periods of intermittent or low hot water consumption, current may be supplied to only one heating element, while during periods of high consumption, both elements may be used and such use may be continued until an adequate supply of hot water at the desired temperature is again established in the tank. Other arrangements, dependent upon the particular requirements in the installation, may, of course, also be made.

The use of a plurality of heating elements prevents interruption of service in the event that one of the elements is damaged or becomes inoperative, since one of the other elements may be utilized to provide hot water while the inoperative element is being replaced. In this connection it should be noted that in many cases the heating elements may be of a standard, readily available type such as used for electric ranges. Thus, replacement of such elements may be readily accomplished and the obtaining of a new element of proper size will not constitute a problem.

It will be understood that bothv the tank 11 and the heater casing 29 will, in. practice, be thoroughly insulated to prevent loss of heat therefrom. For simplicity of illustration the insulation, which may be of any of the various well known types, has not been shown in the accompanying drawings. Furthermore, various changes may be made in the embodiment illustrated without departing from the spirit of the invention. For example, if desired, the storage tank 11 may be of any other desired and suitable shape, additional heating means may be provided, or the heating elements may be of different shapes or sizes. Accordingly, the invention should be given a broad interpretation and should not be considered as limited in scope except by the appended claims.

I claim:

1. In an electric water heater adapted for connection to a water storage tank and convection heating of water in said tank, the combination of a casing, a first watertube coil within said casing, a second water-tube coil disposed within said casing above and spaced from said first coil and formed of tubing having a greater interior diameter than said first coil, said coils being formed as fiat spirals and each coil having an inlet and an outlet, a tubular connection between the outlet of the lower of said coils and the inlet of the other of said coils, and an electrical heating element associated with each of said coils.

2. In an electric Water heater adapted for connection to a Water storage tank and convection heating of Water in said tank, the combination of a casing, a first watertube coil within said casing, a second water-tube coil disposed within said casing above and spaced from said first coil and formed of tubing having a greater interior diameter than said first coil, said coils being formed as flat spirals and each coil having an axial outlet and a peripheral inlet, a tubular connection between the outlet of the lower of said coils and the inlet of the other of said coils, and an electrical heating element associated with each of said coils.

3. In an electric water heater adapted for connection to a water storage tank and convection heating of water in said tank, the combination of a casing, a first Watertube coil Within said casing, a second water-tube coil disposed within said casing above and spaced from said first coil and formed of tubing having a greater interior diameter than said first coil, said coils being formed as fiat spirals and each coil having an axial outlet and a peripheral inlet, a tubular connection between the outlet of the lower of said coils and the inlet of the other of said coils, and a plurality of electrical heating elements, one of said elements being'located in contact with a flat face of each of said coils.

4. In an electric Water heater adapted for connection to a water storage tank and convection heating of Water in said tank, the combination of a casing, a first Watertube coil within said casing, a second water-tube coil within said casing above said first coil, said second coil being formed of tubing having a greater interior diameter than said first coil and being spaced from said first coil 9. distance equal to several times the diameter of said tubing, said coils being formed as flat spirals and each coil having an axial outlet and a peripheral inlet, a tubular connection between the outlet of said first coil and the inlet of said second coil, and a plurality of electrical heating elements, one of said elements being removably mounted in contact with a fiat face of each of said coils and at least one of said elements being removable from said casing without removing either of said coils from said casing.

References Cited in the file of this patent UNITED STATES PATENTS 890,053 Henriksen June 9, 1908 1,077,035 Boyer Oct. 28, 1913 1,373,809 Hadaway Apr. 5, 1921 1,640,048 Nesrnith Aug. 23, 1927 1,654,551 Muhleisen Jan. 3, 1928 

